Department MTM, Katholieke Universiteit Leuven · PDF fileJute-coir hybrid composite panels...
Transcript of Department MTM, Katholieke Universiteit Leuven · PDF fileJute-coir hybrid composite panels...
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i-SUP2008, Natural Fibre Composites
Natural Fibre Composites;Recent Developments
Aart van Vuure
Technological Advisor Composite Materials Sirris
and
Composite Materials Group (CMG)Department MTM,
Katholieke Universiteit Leuven
Flax Hemp Kenaf Sisal
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i-SUP2008, Natural Fibre Composites
Introduction
What? Focus on natural FIBRES
* with Thermoplastic and Thermoset polymer matrices
* with Biodegradable and non-Biodegradable matrices
* with natural, bio-based (“renewable”) and petroleum based (“synthetic”) matrices
What is a “Green” Composite?
Term “Bio-composites” usually reserved for bio-compatible, medical composites
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i-SUP2008, Natural Fibre Composites
Introduction
Why?1) Environmental reasons:
• Renewable resources
• Thermally recyclable, biodegradable, CO2 neutral
• Low energy consumption (low CO2)
So: low “Carbon footprint”
2) Cost: often (potentially) low cost (not silk)
3) Health & safety: less abrasive, more pleasant to handle
4) Good specific mechanical properties
5) Natural image, design aspects
6) Others, like good acoustic damping, low CTE
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i-SUP2008, Natural Fibre Composites
Introduction; Carbon footprint
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i-SUP2008, Natural Fibre Composites
Introduction
Some data on energy utilisation for fibre production:
Lignocellulosic fibres: 4-15 MJ/kg
Natural Fibre Mat: 9.7 MJ/kg
Glass Fibre: 30-50 MJ/kg
Glass Fibre Mat: 55 MJ/kg
Carbon Fibre: 130 MJ/kg
Hemp can store about 0.75 kg of CO2 per kg of fibres during growth
Hemp releases 10 MJ/kg upon incineration (with energy recovery)
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i-SUP2008, Natural Fibre Composites
Introduction
How?* First focus on fibres (starting with traditional matrices)
* Replacement of synthetic fibres, particularly glass; opening opportunities for composites in developmental countries
When?• Last 10 – 15 years!
Who?• Europe: automotive: flax and hemp and “exotic fibres” (jute, sisal, ananas, coir)
• USA: Wood Polymer Composites (WPC): recycled wood dust and plastic waste: deckings
• Developmental world: cheap local fibres instead of glass fibre
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i-SUP2008, Natural Fibre Composites
Introduction, Applications
Mixed natural fibres with PP and UP matrices
Jute-coir hybrid composite panels
Renault Ellypse concept car: natural fibres for acoustic damping
Where?
Flaxcat (NPSP)Flax fibrecatamaran
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i-SUP2008, Natural Fibre Composites
Applications
Flax-Carbon hybrid bike (JEC 2007)(prepreg technology)
Jute-PP suitcase (latex impregnation)
Mixed NF - PP (Injection Moulding) Mixed NF – PP? inner door panel(s)
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i-SUP2008, Natural Fibre Composites
Issues (of Research!)
1) Fibre properties:
* Understanding mechanical properties: e.g. why is silk so tough?
* Natural variability: H2 control cultivation and minimise weather impact?
* Moisture sensitivity: Make fibres more hydrophobic?
* Temperature resistance
2) Environmentally friendly matrices:
* Biodegradable?
* from renewable resources
3) Interface:
* New materials, so research needed to compatibilise (wetting and adhesion)
* Optimising physical-chemical characteristics (surface tensions)
* complex fibre surfaces
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i-SUP2008, Natural Fibre Composites
Issues (of Research!)
4) Processing
• Extraction and separation: How not to damage the technical fibres?
• Control of fibre length and orientation
• Managing moisture: prevent steam & foam formation!
• Composite processing: usually same processes as for Glass and Carbon
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i-SUP2008, Natural Fibre Composites
Natural Fibres
PLANT / Lignocellulosic FIBRES
Wood Stem/Bast
FlaxJute
HempKenafRamie
Leaf
SisalAbaca
PineappleBananaFique
HenequenPalm
Seed/Fruit
CottonCoconut
Grass
BambooRice
ANIMAL FIBRES (protein)
SoftwoodHardwood
SilkWool
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i-SUP2008, Natural Fibre Composites
Natural Fibres, Quantities
Estimated annual production, in millions of tons:
Wood 1750
Steel 800
Cement (800) (before China boom)
Plastics/polymers 120
Composites (polymer) 1.5 mainly glass fibre composites
Glass fibre (composites) 0.6 at 42 wt% in composites
Carbon fibre 0.035 (= 35,000 tons)
Synthetic fibres 30
Natural fibres 27
WPC (0.5) extrapolated from 0.1 in Europe
Plant fibre in composites 0.040 in automotive applications Europe
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i-SUP2008, Natural Fibre Composites
Natural fibres; Quantities
2000 all Europe automotive: 28,000 tons of NF
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i-SUP2008, Natural Fibre Composites
Natural Fibres; properties
1.7-2.125-50400-7001.3kenaf
~2.81303600-41001.44Kevlar 49
~2235~40001.4Carbon
~2.5721200-18002.5E-glass
20-404-6150-1801.2coconut/coir
2-510-30300-5001.5sisal
~230-50500-7401.4bamboo
1.2-3.020-50300-7001.3jute
1.6-4.030-60350-8001.48hemp
1.5-4.050-70500-9001.45flax
28-30~301300-20001.3Spider silk
18-20~16650-7501.3-1.38B. mori silk
elongation atfailure (%)
Young’s modulus
(GPa)
tensile strength(MPa)
density(g/cm2)
material
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i-SUP2008, Natural Fibre Composites
Matrices
Classification of matrices:
* Thermoplastic (TP) and thermoset resins (TS)
Most well-known polymers:PP, PE, nylons, etc.Epoxy, UP
PBSPCLPVA
“Synthetic” petroleum based polymers
Furan resinVegetable oil -PUR (polyol)Wood based epoxy resinEpoxidised soy oil?Ethanol based PE
Cashew nut shell resin?Non-biodegradable
Corn based TP polyesterPLA, PLA-LPHA, PHBStarch based polymersSoy protein resin
Gluten resin?Starch based emulsion?
Biodegradable
Bio-based polymers (renewable feedstock, synthesized!):
Natural polymers:(renewable)
Examples of polymers
• Research on renewable matrices is relatively recent
• Existing systems often have relatively poor mechanical properties
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i-SUP2008, Natural Fibre Composites
Matrices; commercial bio-based polymers
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i-SUP2008, Natural Fibre Composites
Case studies; Research at KU Leuven
1) Silk composites: tough
2) Flax&hemp composites: high performance
3) Bamboo composites: Glass replacement
4) Coir composites: cheap and abundant
5) Wood – PVC compounds and extruded profiles
6) Paper honeycomb panels
1) (Renewable gluten based resin)
2) (Tree bark fibre composites (Art Nature Design))
3) (Jute composites (VLIR project Bangladesh))
4) (Natural Fibre panels for landmine protection)
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i-SUP2008, Natural Fibre Composites
failure strain and stiffness for different high performance and natural fibres
1
10
100
1000
0 20 40 60 80 100 120 140
specific stiffness (GPa.m³/kg)
failu
re s
trai
n (%
)
Silk (Bombyx Mori)Silk (Spider)Flax(E)-Glass fibreCarbon-FibreAramide FibrePolyethylene fibrePolyester fibreLDPE
1) Silk composites
What makes silk fibres special?
LDPE
Bombyx mori silkSpider silk
PE fibreAramid fibre
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i-SUP2008, Natural Fibre Composites
1) Silk composites
Excellent falling weight impact performance!
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i-SUP2008, Natural Fibre Composites
1) Silk Composites
* No clear indication of effect interface strengthfor tough matrices
Effect weakinterface
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i-SUP2008, Natural Fibre Composites
1) Silk Composites
Effect of polymer matrix, aramid fabric composites
0
10
20
30
40
50
60
70
80
Aramid
fabric PP
PBS
TPU
Copoly
amide
PA11
PA46A
bsor
bed
impa
ct e
nerg
y (J
/mm
)
• Hypothesis is that interface properties (impregnation and adhesion) play a crucial role here (weakest is best..)(all matrices have relatively high strain to failure here)
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i-SUP2008, Natural Fibre Composites
2) Flax fibre compositesFlax-epoxy
Transverse flexural strength [MPa]
0
5
10
15
20
25
30
UNTREATED NaOH 1% NaOH 2% NaOH 3%
Alkali treatment leads to stronger interface
Vf: 40 vol%Time: 20 min
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i-SUP2008, Natural Fibre Composites
2) Flax fibre compositesFlax-epoxy
Longitudinal flexural strength [MPa]
0
50
100
150
200
250
300
350
UNTREATED NaOH 1% NaOH 2% NaOH 3%
+ 30%
Fibre treatment with alkali leads to better interface strength
Vf: 40 vol%Time: 20 min
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i-SUP2008, Natural Fibre Composites
3) Bamboo fibre composites
Projects with Columbia and Vietnam (BelSPO)
Extraction of technical bamboo fibres (length ~ 30 cm !):
• Existing processes such as steam explosion and mechanical crushing lead to extensive fibre damage
• New process developed in Columbia and at KU Leuven:
* Strongly reduced fibre damage
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i-SUP2008, Natural Fibre Composites
3) Bamboo fibre composites
GuaduaAngustifolia
• Growth up to 20 cm/day
• Grows to 20 m in 6 months
• Matures in 4 years; can be used after 1 year
• Fixes 54 tons of C/ha
Culm with vascular bundles Technical
fibre(s)
Elementary fibres
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i-SUP2008, Natural Fibre Composites
3) Bamboo fibre composites
150
250
350
450
550
650
750
850
0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0
Extraction method
Stre
ngth
(MPa
)
Mechanical(rolling mill machine)
Chemical extraction(in some cases
mechanical process is required)
Steam explosion
Mechanical process(in some cases chemicalprocess is required)
KULeuven process
Loop test
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i-SUP2008, Natural Fibre Composites
3) Bamboo fibre composites
1. Bagasse2. Coir3. Sisal4. Cotton5. Kenaf6. Henequen7. Jute8. Hemp9. Pineapple10. Ramie11. Flax12. Bamboo13. Curauà14. E-Glass
1. Coir2. Sisal3. Cotton4. Kenaf5. Henequen6. Jute7. Hemp8. Pineapple9. Ramie10. Flax11. Bamboo12. Curauà13. E-Glass
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i-SUP2008, Natural Fibre Composites
3) Bamboo fibre composites
Good performance for untreated bamboo in epoxy• Only limited effect of alkali treatment
Natural Fiber composites Thermoset matrix Flexural strength
0
50
100
150
200
250
300
350
11 2 3 4 5 6 7 8 9 10 11
1. Bamboo (G. ang.) + Epoxy
2. Flax + Epoxy
3. Jute + Epoxy
4. Jute + Vinylester
5. Hemp + Epoxy
6. Sisal + Epoxy
7. Kenaf + Cashew nut Shell
8. Bamboo + Polyester
9. Kenaf + Polyester
10. Hemp + Polyester
11. Hemp + Cashew nut Shell
Figure 67. Flexural strength comparison between UD bamboo+epoxy (Vf 48%) and UD natural fibres+thermoset matrix composites; Vf 35% - 60%
Good adhesion for untreated bamboo in epoxy:• Stiffness and strength in longitudinal direction as expected (Vf)• Transverse flexural strength quite good at around 35 MPa
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i-SUP2008, Natural Fibre Composites
4) Coir composites
Project with Vietnam (BelSPO)
1) Measuring basic mechanical properties + microscopic examination
2) Understanding the interfacial adhesion: measurement of contact angles (direct measurements and with Wilhelmy set-up)
100 µm 20 µm
Light microscope pictures of technical coconut fibre
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i-SUP2008, Natural Fibre Composites
5) Wood-PVC
Market for WPC’s is strongly growing, especially deckings in the USA
• Wordwide market around $ 2 billion
• Europe 2005 about 100,000 tons, growing at 10-20% / year
• Started with recycled wood dust and recycled PE and PP (e.g. agricultural waste foil)
• e.g. Deceuninck in Belgium has launched wood-PVC for deckings and other extruded profiles
• environmental benefits e.g.
* replacement for (tropical) hardwood
* replacement for treated soft wood (hazardous chemicals)
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i-SUP2008, Natural Fibre Composites
6) Paper honeycomb panels
Applications of ‘Torhex’ cardboard honeycombs;sandwich panels with NF composite skins
www.econcore.com
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i-SUP2008, Natural Fibre Composites
Bibliography
Main references for this text:
1) Green Composites, Caroline Baillie, CRC Press, 2004
2) Natural Fibers, Plastics and Composites, Frederick T. Wallenberger & Norman Weston, Kluwer, 2004
3) Natural Fibers, Biopolymers and Biocomposites, Amar K. Mohantyet.al., CRC Press, 2005